Green Synthesis And Antimicrobial Activity Of Vanadium Oxide Nanoparticles Using Nyctanthes Arbortristis Aqueous Leaf Extract

Abstract

 The development of green nanotechnology has revolutionized the synthesis of nanoparticles by providing safer, more eco-friendly, and sustainable alternatives to conventional physical and chemical methods. Among the various metal oxide nanoparticles, vanadium oxide nanoparticles (V₂O₃ NPs) have attracted significant attention due to their diverse applications in biomedical, catalytic, and electronic fields. The present study focuses on the green synthesis of vanadium oxide nanoparticles using Nyctanthes arbor-tristis, a medicinal plant known for its bioactive compounds. This biogenic approach not only reduces the use of hazardous chemicals but also provides a cost-effective and scalable method for nanoparticle production. In this work, fresh leaves of Nyctanthes arbor-tristis were used to prepare an aqueous extract, which served as a reducing and stabilizing agent in the synthesis process. The reaction was initiated by mixing the plant extract with 100 mL of 5% NaOH solution and vanadium oxide precursor. A rapid colour changes in the solution marked the formation of vanadium oxide nanoparticles, indicating a successful reduction of vanadium ions by the phytochemicals present in the leaf extract. This colour change served as a visual indicator of nanoparticle synthesis and was further confirmed by ultraviolet-visible (UV-Vis) spectroscopy. The biosynthetic route employed in this study proved to be rapid, simple, and environmentally friendly. UV-Vis analysis showed a characteristic absorption peak indicating the formation of V₂O₃ nanoparticles, confirming the optical properties and successful synthesis. The presence of plant-based biomolecules in the extract plays a dual role by not only reducing vanadium ions to nanoparticles but also stabilizing them and preventing aggregation. To further explore the structural and morphological characteristics of the synthesized nanoparticles, a series of analytical techniques were employed. Fourier Transform Infrared Spectroscopy (FTIR) was used to identify the functional groups involved in nanoparticle stabilization. The FTIR spectra revealed the presence of various biomolecules such as alcohols, phenols, carboxylic acids, and amines, which contributed to capping and stabilizing the nanoparticles’-ray Diffraction (XRD) analysis confirmed the crystalline nature of the synthesized vanadium oxide nanoparticles. The XRD pattern exhibited prominent Bragg reflections corresponding to planes (012), (104), (110), (113), (202), (024), (116), (122), (214), (300), and (1010), which matched the standard data for face-centered cubic (fcc) V₂O₃. These results verified the crystalline structure of the particles and their phase purity. Morphological studies were conducted using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). SEM images provided insight into the surface structure and general shape of the particles, while TEM offered higher-resolution images that revealed uniform dispersion of nanoparticles. TEM analysis showed that most particles were spherical to slightly irregular in shape and ranged in size from approximately 1 to 500 nm. Although a generally homogeneous distribution was observed, some degree of agglomeration occurred, which is common in plant-mediated syntheses. Energy Dispersive X-ray Spectroscopy (EDX) was performed to confirm the elemental composition of the nanoparticles. The EDX spectra confirmed the presence of vanadium, along with oxygen and trace elements derived from the plant extract. These results validated the successful synthesis of vanadium oxide nanoparticles with minimal impurities. The synthesized nanoparticles were also evaluated for their antimicrobial properties. The antibacterial activity of V₂O₃ nanoparticles was tested against several clinical bacterial isolates. Results indicated that the nanoparticles exhibited stronger antibacterial effects than the crude plant extract, demonstrating broad-spectrum efficacy. This enhanced activity is likely due to the small size and increased surface area of the nanoparticles, allowing better interaction with microbial membranes.